To examine the genuineness and value of coins, different examining systems and examining equipment are already known, which detect and evaluate the characterizing distinguishing features of coins, such as the geometric dimensions, the material, the weight or the milled edge.
The examining methods can therefore be divided into mechanical, inductive and optical method, the mechanical construction of the coin-examining apparatus logically being determined by the examining method used.
In the case of optical methods of examining, it is known that the coins to be examined roll or are conducted on a guiding channel past optical sensors in order to detect characteristic points and/or parameters of the coin. The accuracy of the measurement is determined here by the number of the sensors present and by the length of the guiding channel. It follows from this that, at very high degrees of accuracy, a larger number of optical sensors and a guiding channel of appropriate length are required, which, in turn, lead to relatively large and expensive examining equipment. Small, compact and accurate examining facilities can be realized only with great difficulty with this technique.
Other solutions are known, in which the coins are clamped between three wedge-shaped rollers, which are disposed in the shape of a triangle and are turned through the agency of a motorized driving mechanism of one of these rollers due to friction pairing between the driven roller and the coin.
The mechanical effort involved in realizing a plane-parallel and centric running of the coin with this arrangement of rollers is very high and susceptible to failure, since the coin driving mechanism is a frictional wheel driving mechanism.
Furthermore, the degree to which the coins are soiled, which negatively affects the friction pairing with respect to the constancy of the rotational speed, must be taken into consideration.
Increasingly, opto-electronic coin-examining equipment and methods are also being used, which make it possible to scan accurately the minting or selected sections of the minting and/or the milled edge of a coin.
This equipment ensures a highly accurate determination of the genuineness and the value of a coin and leads to equipment configurations with a high degree of accuracy in the identification of genuine money and the rejection of counterfeit money.
For opto-electronic coin-examining equipment working with high accuracy, an accurate and exact gripping and centering of the coin to be examined is, however, a prerequisite for the subsequent opto-electronic scanning, since the smallest inaccuracies and deviations in the gripping, centering and examining of the coin during the scanning process lead to wrong interpretations and breakdowns.
Particularly in the case of mobile coin examining equipment with opto-electronic examining systems, care must be taken to ensure that, despite the vibrations and oscillations, which cannot be avoided, the exact mounting and guidance of the coins during the examining cycle is ensured and wrong interpretations are reliably avoided.
An important disadvantage of known coin-examining equipment consists particularly in that, for examining further characteristic parameters, such as the material of the coin, additional or separate examining sections must be provided in the equipment in question. These additional examining sections, in turn, require further construction space, of which there is anyhow very little to spare.